Fourier Transform Infrared Spectroscopy (FTIR) allows the non-destructive acquisition of the infrared emission and absorption spectra of solid, liquid or gaseous samples. This spectral signature is obtained after processing the raw data by Fourier transformation.

Each functional group has a specific resonance frequency. 

The FTIR technique is based on transitions between vibrational energy states. A chemical bond can be compared to a spring, with the atoms being masses attached to its ends. When an electromagnetic radiation (infra-red), with a frequency close to the natural vibrational frequency of this bond crosses the sample, the light beam is absorbed.

The spectra acquired in FTIR provide information on the different functional groups present in an organic/inorganic sample.

The wavelength of each IR vibrational absorbance peak is representative of the intrinsic chemical bonds of the analysed molecule. It can be assimilated to the fingerprint of the corresponding functional groups (for example, C-H, O-H, C=O, etc.). A beam of photons in the IR wavelength range (400 to 4000 cm^-1) is used as an excitation source for the sample to be analyzed: the signal resulting from its absorption/transmission by the sample is directed to a Michelson interferometer which consists of a set of
 

reflective or semi-reflective mirrors, fixed or mobile. Depending on the configuration of the mirrors, each wavelength is periodically stopped or transmitted towards the sample before being collected on the detector, which records all the data for a reprocessing Fourier-Transform software. The obtained transmittance or absorbance spectrum provides information on the absorption bands which depend on the nature of the chemical bonds (single or multiple), the atoms involved and their environment within the molecule.

The absorbance intensity of each peak is proportional to the concentration of the functional groups. 

It is possible to quantify the concentration of functional groups present in a sample, by comparing the intensities of the vibrational bands measured on a sample with a previously calibrated curves. Micro-FTIR characterization can be performed in transmission or reflection mode. Equipped with an ATR (Attenuated Total Reflection) and a microscope, our FTIR spectrophotometer performs analysis in three modes: FTIR spectroscopy in transmission mode, FTIR spectroscopy in ATR mode and micro-FTIR in imaging mode. Signals are collected with a high spatial resolution of a few micrometers. 

The coupling of an infrared with a microscope allows the visualization and the mapping of functional groups at the micrometer scale.

 

SPECTROSCOPY MODE 

Acquisition of a transmittance/absorbance spectrum
The transmitted waves are detected after the interaction of an IR beam with the sample in transmission, ATR or micro-FTIR mode.
 

MAPPING MODE

Imaging the distribution of one or more functional groups on the surface of a sample
Acquisition of IR spectra pixel by pixel on a given surface.

Micro-FTIR technical specifications

• Type of detector: DTGS
• Spectral range: 7800 - 400 cm^-1
• Signal detected: transmission, reflection and ATR
• Detected elements: molecular functional groups
• Type of analysis: qualitative & quantitative
• Signal to noise: 2100 - 2000 cm^-1 (100 μm): Better than 25,000:1
• CCD camera

Micro-FTIR strengths

• Analysis of a wide range of organic and inorganic materials
• Identification of functional groups 
• Quantitative method
• Chemical mapping of the surface of a sample with micrometric lateral resolution